Grażyna – Part IV

Rivets
From: Steel ships; their construction and maintenance: a manual for shipbuilders … pub. 1904 pg. 175

A rule that should be observed in all rivet work is that no rivet should come nearer to the edge of any plate than it’s own diameter. In connecting two plates or two angle bars or a plate and an angle bar in any important structural part, the greater thickness regulates the diameter of the rivet to be used. The corresponding diameters of rivets for plates or angles increasing in thickness is given in the adjoining table (below).

table_of_riveting

This gets interesting when we look at what material we will be using to plate the model. A aluminum Coke can is about .004 in. thick. That would be 0.192 in. full size (or about \frac{4}{20} in that strange (to me) way the numbers are displayed in the table). If I used 0.010 in. brass instead that would be 0.48 in. full size or about \frac{9}{20}. If I used the .004 in. aluminum than from the chart I should be using a \frac{5}{8} in. rivet – and if I used the .010 in. brass a \frac{3}{4} in. rivet. Not that it makes any difference at this scale but at least we have a starting point when picking through available rivets for modeling this in O scale.

Example: Looking at the Archer Surface Details decals .. the Tank car double-row (staggered) rivets are .020 in. .. or ~1 inch. From the table that would be the rivet used for a plate larger than shown on the table!

The S-scale Tank car double-row rivets are .014 in. dia. which would be equal to a .672 in. dia. rivet. That would be just a little over the \frac{5}{8} rivet.

So .. to the HO scale Tank car double-row rivets .. and there is no size shown! Well .. HO is 55% of O so that should make them right at .011 in. dia. That converts full-scale to .528 in. or darn close to \frac {5}{8} in. – which is the correct size rivet for plates with thicknesses from \frac{1}{4}\:to\frac{5}{16} in. The .004 in. aluminum would be close .. at .192 in just a little under the .250 in. plate. Reduced to 1:48 the difference is only about .002 in. plates with thicknesses from 1/4 to 5/16 in. The .005 in. K&S aluminum sheet I found would be .240 in. – more than ‘good nuff’ to match the \frac{1}{4} in. plate. With the slightly smaller .528 rivet it would work fine (IMO)

Again .. the point isn’t that I’m trying to make it exactly to scale .. no .. trying to get an idea of what DOES work and is in scale. If it can be used .. then why not? The .005 aluminum sheet and the Archer S or HO Tank car double-row rivets would .. work together. If I had other rivets or materials on hand then sure .. use them. If though I have to order the things then .. shrug .. why not get the ones that are correct (or near so)?

Materials
alumimumandrivetsCurrently – the plan is to go with the K&S Aluminum Sheet. It is .005 thick 36 gauge measuring 12″ x 30″ – Stock #6025. The sticker cost at Hobby Lobby was $5.99 .. but I had one of those 40% off coupons which dropped that to about $3.60 .. love those coupons! The Archer HO scale Tank car double-row rivets AR88031 contain 100 linear inches of rivets.

The $17.95 cost for a piece of paper measuring only 2.75 x 4.5 inches is quite .. amazing .. but I was thinking.

The ship is 25 inches long – and is ~ 1 inch high which means I need to plate 50 sq. inches of ship. The double-row rivets are used where plates overlap so figure minimum one row of visible rivets the length of the ship. The ship is at the waterline and if each plate is say .. three foot tall then we would have two rows of plates visible – hence one double-rivet row of rivets visible. The bulwark isn’t part of the structure of the ship as such and I think can get away with a single row of rivets. The ship was built c. 1890 so there would have been a lot of manual labor working the plates – meaning they had to be manhandled which reduces the maximum size that a man or two can easily manipulate – remember that they have to be curved to fit the ship frames so they are run through various machines or pounded with hammers to get that curve. I figure if the frames are say .. 3 ft. apart (3/4 inch O scale) then let the plates be 6 foot long (1-1/2 inches O scale). That would mean about 17 vertical joints each 1 inch long for a total of 17 inches of double-row rivets. That totals 84 linear inches of double-row rivets for both sides of the ship so the single Archer HO scale rivet sheet should work. I still need a second source for the single row rivets.

– stream of consciousness –
If someone happens to land on this page don’t be surprised if you return and it has changed. This is a place really for me to place notes to myself. Just how many rivets might be used .. and where will change as I gather more information. I get the feeling that in the early days there were no hard and fast rules. I can find photos of ships with single rivets horizontally. What size should the plates be? I can ‘guess’ that I will make mine 3ft x 6ft as I stated earlier .. but that can change easily enough. I just have to state that .. “I don’t know anything” .. so when I am pointed at better information I will change my plans.
Bulwarks, Sheer Strake etc.
Fig9I found this illustration in Steel ships; their construction and maintenance: a manual for shipbuilders … pub. 1904 pg. 43 Fig.9. A close up look gives us a lot of information. The Sheer Strake overlaps the bulwark. The deck sheathing stops shy of the stanchions up against a margin plate. A waterway runs down the length between the sheathing and the bulwark. Good stuff.

A search for “margin plate” let me to the Titanic Research & Modeling Association’s page on Wooden Decks by Bruce Beveridge. Wow! Tons of info just on that one page.

Plating Pattern
rivetpatternThis is an early try at arranging the plating. The diagram is a bit unclear as to the plate height on the stern – the plates sit on the inward curve. At the very top the Sheer Strake is only shown 1/8 in. (6 in.) tall. I may increase that. The first place to work I think will be what I have labeled the ‘Stern Belly’ .. then the opposite end up under the prow.

The location of the Bulkhead ends is just approximate on the hidden frames. The actual location depends on the size of the forecastle for the front and the size and location of the aft superstructure/bridge.

SAMSUNG DIGITAL CAMERAThis photo showing the riveted plate of a ship’s stern is a pretty good example to help me figure out how to wrap the plate around the stern of my ship. I tell myself that.

Looking closer the strakes are single-row riveted with lapped edges. The ends are butt strap riveted. Note there are three rows of rivets on either side of the joint with the outside row missing every other rivet (caulk side) .. standard procedure. The plates are single-row riveted to the frames. Notice also the plates are tapered to fit the curve.

Stern belly
belly_1My first try at determining how to plate the ship. If I leave what is basically a 1/8 in. rabbeted edge around the deck for the bulwark to attach to .. and trying a 3/4 in. wide plate below that, I cut a piece of tape 7/8 in. wide. The plan was/is to start by plating up to the tape. I noticed that I need to fill in the space circled in red.
belly_2I sliced off a chunk of balsa and sanded it so it would fit snugly into the opening. Glued well and let the glue set up well. Again, not too concerned with it being a perfect job … this will just support the overlay of plating.
Decking and Margin Plate
fig-144This illustration was taken from ‘The Elements of Wood Ship Construction Part I’- copyright 1918. from pg.30. I colored the planks green and the margin plate blue.

The wood decking of large vessels is separated from the side of the ship, or bulwark, by a gutter way. The outer boundary of the decking is formed by a wide plank, which is variously known as a plank sheer, margin plank, or as on wooden vessels, a covering board. Other wide planks are also fitted around hatches and scuttles, at transverse boundaries, and as foundations around barbettes, winches and other machinery. These margin pieces should, when possible, be teak1

fig-144-2Looking at how the deck plates are notched into the margin plate. I plotted the distance into the margin plate they were notched by setting the margin plate on one end to 1. With the center at each maximum notching we have .817, .841, .850, .833, .799. So .. it averages .83 the width of the margin plate. If these circles lie on the edge of the deck then I should be able to plot the deck timber notching easily enough with a simple jig. The two lower plank shown don’t notch into the margin plate but butt against it. It appears to me that for each plank notched into the margin plate there is a long side that parallels the outer edge of the margin plate .. more or less. The short side is at 90° to the long side. The two lower planks with the long side parallel to the outer edge leaves no room for the short side. That short side is .25 the width of the margin plate .. or .. .25 x .174 = about .040 in.

I didn’t put it on the drawing but the planks are about 70% the width of the margin plate – or looking at it from the other direction .. the margin plate is about 1.4 x the deck plank width. Since my deck planks are 6 in. (1/8″) the margin plate is 8.4 in. (.175″)

Let’s see .. what else? umm .. .83 x .175 = .145 .. that would be the jig dia. to set the notch distance.

fig-144-3This morning I was sitting here looking at the way the planks nib into the margin plate. It looks like that below 30° they step with a short and long side while above that 30° the plank fits against the side of the margin plate. Is this helpful? Perhaps – in any case it can’t hurt.

  1. Wooden Decks by Bruce Beveridge []

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